In one form of known prior art the fabrics are made of polyester produced in two layers, with an inner layer being completely formed of a hydrophobic form of polyester and the outer layer being formed of treated polyester which is hydrophilic. These hydrophilic treatments are applied as chemical treatments to the polyester, and unfortunately it has been found that the fabrics lose their hydrophilic treatment on washing and they therefore deteriorate from both a comfort viewpoint and a technical performance viewpoint.
Hydrophobic materials may be weakly hygroscopic, such as polyesters and polyacrylonitriles, which have a low water-retention of less than about 25%, or non-hygroscopic, such as polpropylene, polyvinyl chloride or polyethylene.
Hydrophilic materials tend also to be strongly hygroscopic, such as cellulose or wool.
It has also been proposed in published US Patent Application 2004/0058072 to produce fabrics from yarns in which there is a first yarn of cellulosic fibres, part at least of which is treated with a hydrophobic treatment, and a second yarn of cellulosic fibres with a higher absorbent capacity than the first yarn, the fabric being produced by knitting or weaving together the first and second yarns so that the inside surface has a lower absorbent capacity than the outside surface.
Again, these types of processes involve the chemical treatment of the fibres to give the desired effect, and such chemical treatments are not permanent and wash off in use.
WO-A-98/24621 discloses a unitary stratified composite, apparently for diapers or other hygienic products in which liquid from the wearer's body is to be absorbed. The composite is composed of a first stratum serving as a liquid acquisition stratum that rapidly acquires liquid from the wearer and transfers it through a transition zone to a second stratum which serves as a temporary storage medium. Both strata comprise fibres and a binding agent, and the composite in use has an outermost external surface which does not leak or absorb moisture from outside.
U.S. Pat. No. 5,433,987 discloses a spun-laced fabric having improved water absorbency to absorb perspiration and other body fluids and collect or disperse the same away from the body for the comfort or hygiene of the wearer. The fabric is used as an absorbent layer in a multilayer or laminate structure but does not form the outermost layer facing away from the wearer in use in a garment.
Other known prior art documents of lesser relevance are US-A-2003/0181118, U.S. Pat. No. 5,787,503, U.S. Pat. No. 5,735,145 and U.S. Pat. No. 5,297,296.